public static int gemstones(List<String> arr) {
    // Write your code here
    int count=0; 
    String alphabet = "abcdefghijklmnopqrstuvwxyz";
    for (int i = 0; i < alphabet.length(); i++) {
        boolean flag = true;
        for (String str : arr) {
            if(!str.contains(String.valueOf(alphabet.charAt(i)))){
                flag = false;
            }
        }
        if (flag) {
            count++;
        }
    }
    
    return count;

    }

int gemstones(vector<string> arr) {
    int result = 0;
    string liste = "abcdefghijklmnopqrstuvwxyz";
    for(int j = 0; j < liste.size(); j++){
        int cp = 0;
        for(int i = 0; i < arr.size(); i++){
            if(arr[i].find(liste[j]) != string::npos) cp++;
        }
        if(cp == arr.size())result++;
    }
    return result;
}

string getShortest(vector<string> arr) {
    string result = arr[0];
    for(int i = 1; i < arr.size(); i++){
        if(arr[i].size() < result.size()) result = arr[i];
    }
    return result;
}
int gemstones(vector<string> arr) {
    int result = 0;
    string shortest = getShortest(arr);
    set<char> liste(shortest.begin(), shortest.end());
    for(auto j = liste.begin(); j != liste.end(); j++){
        int cp = 0;
        for(int i = 0; i < arr.size(); i++){
            if(arr[i].find(*j) != string::npos) cp++;
        }
        if(cp == arr.size())result++;
    }
    return result;
}

def gemstones(arr):
    sets = [set(i) for i in arr]
    return len(set.intersection(*sets))

import java.io.*;
import java.util.*;

public class Solution {
    public static void main(String[] args) {
        /* Enter your code here. Read input from STDIN. Print output to STDOUT. Your class should be named Solution. */
        Scanner input = new Scanner(System.in);
        int n = input.nextInt();
        input.nextLine();
        
        Set<Character> gemstones = stringToSet(input.nextLine()); //Set of gemstones
        
        for(int i=1; i<n ;i++){
            gemstones.retainAll(stringToSet(input.nextLine())); //Perform intersection
        }
        System.out.print(gemstones.size());
    }
    
    
    
    
    public static Set<Character> stringToSet(String s) //Converts String to Character set
    {
        Set<Character> set = new HashSet<Character>(26);
        for (char c : s.toCharArray())
            set.add(Character.valueOf(c));
        return set;
    }
}

function gemstones(arr) {
    // Write your code here
   let alp=arr[0].split('');
   let newarr=new Set();
   for(let x=0;x<alp.length;x++){
      let found=true;
      for(let i=1;i<arr.length;i++){
       if(arr[i].indexOf(alp[x])==-1){
           found=false;
       }
     } 
     if(found){
         newarr.add(alp[x]);
     }
   }
   console.log(arr,newarr)
   return newarr.size;